PWE3 is a mechanism that simulates various point-to-point services on Packet Switched Network (PSN); the simulated services may be various networks such as Time Division Multiplex (TDM) private wire network, Asynchronous Transmission Mode (ATM) network, Frame Relay (FR) network or Ethernet. PWE3 utilizes tunnel mechanism on the PSN to simulate required attributes of the services; wherein the tunnel is called as Pseudo Wire (PW). A provider can utilize PWE3 to transfer all transmission services to a converged network, here the converged network may be IP is network or Multiple Protocol Label Switching (MPLS) network and the like. For users, the required attributes simulated by PWE3 can be considered as a dedicated link or circuit.
FIG. 1 shows a structure diagram of a service reference model of PWE3 on the PSN, which is proposed by Internet Engineering Task Force (IETF. As shown in FIG. 1, PE1 and PE2 are provider edge devices, CE1 and CE2 are customer edge devices, one or more PWs, namely PWE3 channels, are established between the PE1 and the PE2, Access Links (AC) are established between the CE and the PE, and the AC may be Ethernet and may also be non-Ethernet, such as the ATM network. After the CE1 and the CE2 are accessed to the PE1 and the PE2 through the AC respectively, communication between the CE1 and the CE2 is implemented through the PW. PW is borne on a PSN tunnel, and the PSN tunnel determines the data forwarding path. One PSN tunnel can bear multiple PWs. When communication is implemented between the CE1 and the CE2, the user data of CE1 is first encapsulated with a PW label after the user data is transmitted to the PE1, and then encapsulated with a tunnel label and Medium Access Control (MAC) address to form a data message. The data message is transmitted to the PE2 through a path established by the PW, and the PE2 de-encapsulates the received data message and takes out the PW label to determine an exit circuit; the user data obtained by the de-encapsulation is transmitted to the CE2. The model shown in FIG. 1 is a reference model of PWE3 in practical application, which can implement pseudo wire emulation edge-to-edge access for Ethernet or non-Ethernet; the basic principle of the model is universally applicable for practical application, the specific application modes of the model are different when the specific service demands are different.
At present, the method for pseudo wire emulation edge-to-edge access for non-Ethernet is that the PWE3 services are implemented by exchanges of multiple PWs, namely, PW encapsulation is performed on local user data before the local user data is is transmitted to the local PE, the PW label in the PW encapsulation is assigned by the local PE, wherein the PW is only the PW between the local user and the local PE; the local PE uses the PW label assigned by the opposite PE to replace the PW label in the data after receiving the data, wherein the PW is the PW between the local PE and the opposite PE and is used to transmit the data at the local PE to the opposite PE; after receiving the data, the opposite PE also needs to replace the PW label again to transmit the data to the opposite user. Here, the local PE or the opposite PE needs to assign different PW labels for different users, if the local PE or the opposite PE corresponds to multiple users, the PW labels of the multiple users will occupy a large amount of label space of the PE.